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PubMed1988

Risk factors for stroke in chronic atrial fibrillation.

Atrial fibrillation is associated with an increased risk of stroke. Different risk factors may be of importance regarding stroke incidence and mortality in atrial fibrillation. Retrospectively, we studied 786 patients with chronic atrial fibrillation, 229 with rheumatic heart disease and 557 without. In all, 127 patients had stroke (16%). Using Cox's proportional hazard model for failure-time data with age, gender, etiology, degree of heart failure and cardiac enlargement as explanatory (independent) variables, only etiology (rheumatic heart disease) was a significant risk factor for stroke (P less than 0.006). Significant risk factors for death in 653 patients without stroke were age (P = 0.000) and congestive heart failure at the onset of atrial fibrillation (P = 0.000). The need to identify other risk factors for stroke in patients with atrial fibrillation is emphasized, for selecting patients at high risk for prophylactic treatment with anticoagulants or aspirin.

Adolescent↗

PubMed1997

Risk of complications of atrial fibrillation.

Atrial fibrillation is associated with three major risk of complications: thromboembolism, hemodynamic compromise, and arrhythmogenesis. In patients with chronic atrial fibrillation the incidence of embolization is about 5% per year. The risk of embolism and in particular of stroke can be reduced by warfarin anticoagulation. Aspirin is generally less effective than warfarin, although it is probably more effective than placebo. The hemodynamic complications which may occur during atrial fibrillation are mainly due to the loss of effective atrial contraction, the irregular ventricular rhythm, and the possible excessively rapid ventricular rate. Sudden death is a recognized manifestation of Wolff-Parkinson-White syndrome and is considered to be precipitated by atrial fibrillation in the majority of patients. Torsades de pointes is perhaps the most widely recognized proarrhythmia associated with treatment of atrial fibrillation, especially with 1A antiarrhythmic drugs and sotalol. The chronic treatment with type 1C drugs in 3.5%-5% of patients may induce atrial flutter with 1:1 conduction with significant hemodynamic compromise.

Animals↗

PubMed1991

Value of the atrial signal-averaged electrocardiogram in identifying patients with paroxysmal atrial fibrillation.

Atrial signal-averaged electrocardiogram was compared between 25 patients with paroxysmal atrial fibrillation and 20 healthy persons without atrial arrhythmias (control). The duration time of the high frequency (50-250 Hz) P wave was significantly (P less than 0.01) prolonged in the groups of patients with paroxysmal atrial fibrillation compared with the control group (116 +/- 16.4 versus 92 +/- 8.1 msec). The diagnostic value of the duration of the high frequency P wave for identifying patients with paroxysmal atrial fibrillation was 104 msec. Using this criterion, a sensitivity of 76% and a specificity of 90% were achieved. Our observation has shown that the atrial signal-averaged electrocardiogram is a useful technique for identifying patients with paroxysmal atrial fibrillation.

Adult↗

PubMed2003

Anticoagulation in management of atrial fibrillation.

Atrial fibrillation is the most common cardiac arrhythmia in adults. The prevalence of atrial fibrillation rises with age, reaching as high as 9% in those 70 years and older. Currently there are 2.2 million affected people in the United States, with twice the mortality rate of age-matched controls in sinus rhythm. Epidemiologic studies show atrial fibrillation to be responsible for as many as 15% of the total number of strokes, a higher incidence of dementia, cardiac function compromise, and decreased quality of life. Recent studies indicate that rate control and rhythm restoration are equally effective strategies in the treatment of atrial fibrillation, with a trend toward better survival in patients treated for rate control and anticoagulation. Data from several randomized controlled studies on stroke prophylaxis provided consistent evidence of the superiority of adjusted-dose warfarin over aspirin. Guidelines developed by the American College of Cardiology, the American Heart Association, the European Society of Cardiology, and ACCP provide a convenient decision-making framework for the practicing physician. The safety and effectiveness of anticoagulation in clinical practice were found to be equal to those in major trials with rigorous controls. Despite the proven effectiveness and safety of oral anticoagulation for thromboembolism prophylaxis in atrial fibrillation, warfarin remains underused, especially among the elderly (75 years and older), who are at the greatest risk of stroke and would likely benefit the most from prophylactic anticoagulation.

Anticoagulants↗

PubMed2005

Renin-angiotensin system block and atrial fibrillation.

Atrial fibrillation is the most common disorder of cardiac rhythm. In spite of diagnosis simplicity, patients with atrial fibrillation are difficult to treat. In the recent years with the description of the phenomenon called remodelling, it has been possible to better define the principle mechanisms responsible for initiation, maintenance and, in some instances, termination of atrial fibrillation. Electrical, mechanical and anatomical remodelling indicate those alterations that, once established, may vanish any attempt to restore sinus rhythm. Atrial fibrosis is probably the most critical component of the remodelling process and appears to be largely mediated by the activation of the Renin-Angiotensin-Aldosterone System. Both experimental and clinical data have confirmed the pro-arrhythmic role of the Renin-Angiotensin-Aldosterone System and demonstrated an anti-arrhythmic effects of ACE-inhibitors and AT(1) receptor blockers. Regarding atrial fibrillation, it has been recently reported that the adjunction of AT(1) receptor blocker to amiodarone was more effective than the anti-arrhythmic drug alone, in reducing arrhythmia recurrence after electrical cardioversion. This and subsequent clinical observations indicate that pharmacological interventions capable of interfering with the electrical and structural remodelling process are of critical importance in the management of patients with atrial fibrillation. ACE inhibitors and AT(1) receptor blockers represent new and efficient therapeutical options to contrast the nearly inevitable progression of this arrhythmia towards its permanent form.

Aldosterone↗

PubMed1998

Drugs for conversion of atrial fibrillation.

Atrial fibrillation is the most common arrhythmia in patients visiting a primary care practice. Although many patients with atrial fibrillation experience relief of symptoms with control of the heart rate, some patients require restoration of sinus rhythm. External direct current (DC) cardioversion is the most effective means of converting atrial fibrillation to sinus rhythm. Pharmacologic cardioversion, although less effective, offers an alternative to DC cardioversion. Several advances have been made in antiarrhythmic medications, including the development of ibutilide, a class III antiarrhythmic drug indicated for acute cardioversion of atrial fibrillation. Other methods of pharmacologic and nonpharmacologic cardioversion remain under development. Until the results of several large-scale randomized clinical trials are available, the decision to choose cardioversion or maintenance of sinus rhythm must be individualized, based on relief of symptoms and reduction of the morbidity and mortality associated with atrial fibrillation.

Acute Disease↗

PubMed2001

Underutilization of anticoagulation therapy in chronic atrial fibrillation.

Atrial fibrillation, the most common chronic arrhythmia, results in an increased risk of stroke. Anticoagulation therapy can reduce this risk, but appears to be underused. The objective of this study was to examine the use of warfarin and prevalence of stroke in patients with rheumatic, nonrheumatic valvular and nonvalvular atrial fibrillation. Between January 1993 and December 1998, 457 chronic atrial fibrillation patients with continuous follow-up in our hospital were identified as having rheumatic heart disease (n = 114): nonrheumatic valvular disease (n = 65); or nonvalvular disease (n = 278). Warfarin was used less often in patients with nonrheumatic valvular (16.7%) and nonvalvular diseases (20.1%) than in those with rheumatic heart disease (81.6%, p < 0.001). In contrast, the prevalence of stroke among patients with nonvalvular disease was 40.3% which was similar to the 33.3% found in patients with rheumatic heart disease but significantly higher than the 24.6% found in patients with nonrheumatic valvular disease (p < 0.05). A history of stroke did not alter the trend of use of warfarin among the three groups of patients. Only 20.6% of patients on warfarin received monthly monitoring of prothrombin time. In conclusion, the anticoagulation therapy in our patients with chronic atrial fibrillation, regardless of their associated valvular diseases, is significantly underutilized. This underuse could account for a high prevalence of stroke. This risk of stroke, however, is less in patients with nonrheumatic valvular discase than in those with nonvalvular atrial fibrillation.

Aged↗

PubMed1996

[Prevention of thromboembolism in patients with atrial fibrillation].

Atrial fibrillation is a disorder of the cardiac rhythm associated with an increased risk of thromboembolism. Several studies in the past confirmed that anticoagulation or also antiaggregation therapy is associated in these patients with a reduced incidence of cerebrovascular attacks and peripheral embolism. For a more objective assessment of the risk of individual patients risk factors of thromboembolism in atrial fibrillation were defined. They include cardiac insufficiency, hypertension, a history of embolism, left atrial dilatation, systolic dysfunction of left ventricular hypertrophy and spontaneous echo contrast. This risk stratification of patients with atrial fibrillation is the basis for correct selection of subsequent treatment. In patients without risk factors treatment with acetylsalicylic acid can be recommended, if older than 60 years. In younger patients no treatment is necessary for prevention of thromboembolism in this group. In the presence of one or several risk factors permanent anticoagulation treatment with a target value of INR 2.5 is necessary. In patients with atrial fibrillation associated with a congenital or acquired heart disease warfarin is administered with a target value of INR 3-4. The same approach is used in patients with chronic and paroxysmal atrial fibrillation.

Atrial Fibrillation↗

PubMed1993

Atrial contractile performance after cessation of atrial fibrillation.

Atrial fibrillation is associated with a fall in cardiac output, and cardioversion to sinus rhythm is frequently attempted. After cardioversion, atrial contractile performance might be depressed. It is, however, unclear whether or not atrial contractile performance is altered following atrial fibrillation periods lasting < 1 wk. Atrial contractile performance after short-term paroxysmal atrial fibrillation was examined in seven barbiturate-anesthetized, open-chest pigs paced at constant ventricular rate after complete atrioventricular block. Percent left atrial systolic shortening (systolic shortening of left atrial diameter in percent of atrial diameter at onset of atrial contraction, %LASS) increased from 100 to 116.2% (107.7-121.8) (median and 95% confidence interval) immediately after cessation of a fibrillation period of 1 min. A brief phase of atrial hypercontractility (%LASS significantly above control) was also demonstrated after fibrillation periods of 5 and 15 min. A subsequent phase of atrial hypocontractility (%LASS significantly below control) was recorded after atrial fibrillation periods of 5, 15, and 30 min. After the 30-min fibrillation period, atrial hypocontractility was most pronounced and reached a nadir of 86.8% (75.1-93.3).

Aged↗

PubMed2000

Transesophageal echocardiography risk factors for stroke in nonvalvular atrial fibrillation.

Atrial fibrillation is a common arrhythmia, particularly in the older age groups. It confers an increased risk of thromboembolism to these patients, and multiple clinical risk factors have been identified to be useful in predicting the risks of thromboembolic events. Recent studies have evaluated the role of transesophageal echocardiography (TEE) in the evaluation of patients with atrial fibrillation. The purpose of this review is to evaluate the significance of transesophageal echocardiographic findings in the prediction of thromboembolic events, particularly stroke, in patients with nonvalvular atrial fibrillation, with an emphasis on recently reported prospective studies. Aortic plaque and left atrial appendage abnormalities are identified as independent predictors of thromboembolic events. Although they are associated with clinical events, they also have independent incremental prognostic values. Other transesophageal echocardiographic findings, such as patent foramen ovale and atrial septal aneurysm, have not been found to be predictors of thromboembolic events in this patient group. Thus, TEE is a useful tool in stratifying patients with nonvalvular atrial fibrillation into different risk groups in terms of thromboembolic events, and it will likely play an important role in future studies to assess new treatment strategies in high-risk patients with atrial fibrillation.

Aneurysm↗

PubMed1996

The causes and management of atrial fibrillation.

Atrial fibrillation is present in approximately 10% of the population aged over 65 years, in whom its presence is associated with a significantly increased morbidity and mortality. Principal complications include reduced cardiac output and the precipitation of heart failure and thromboembolic phenomena, including strokes and peripheral emboli. In the majority of cases atrial fibrillation is associated with ischaemic heart-disease and hypertension. Other important causes are thyrotoxicosis, valvular heart-disease and atrial septal defect. The primary aims of treatment in atrial fibrillation are to terminate the arrhythmia (cardioversion) with either drugs or direct current (DC) shock and to prevent its recurrence. Effective cardioversion may necessitate the treatment of underlying pathology. If these primary aims cannot be achieved then an attempt must be made to effectively control the ventricular rate with drugs such as digoxin. Recently, further strong evidence has been provided to support the role of anticoagulants and antiplatelet drugs in preventing the major problem of systemic thromboembolic complications. Some of the special difficulties relating to the treatment of atrial fibrillation associated with thyrotoxicosis as well as paroxysmal atrial fibrillation will also be considered.

Anti-Arrhythmia Agents↗

PubMed2002

Hyperthyroidism and the management of atrial fibrillation.

Atrial fibrillation is often induced in patients with hyperthyroidism and may trigger heart failure. Its prevalence and outcome were examined to obtain up-to-date information. Persistent atrial fibrillation was observed in approximately 1.7% of new hyperthyroid patients. It occurs more frequently in males (2.86%) than in females (1.36%), even though the number of male hyperthyroid patients is only one fifth of female patients. The rate increased with age, being 8% in the patients older than 70 years old. The initial treatment is to control the heart rate with routine pharmacologic therapy and to start antithyroid therapy as quickly as possible. Attempted cardioversion should be deferred until approximately the fourth month of maintaining a euthyroid state, because more than 56% of atrial fibrillation spontaneously reverts to sinus rhythm when the thyroid hormone levels start to decline. Elective cardioversion for those whose atrial fibrillation persists is highly effective and sinus rhythm maintenance rates were 56.7% and 47.6% at the 10th and the 14th year, respectively, even though the duration of atrial fibrillation prior to cardioversion was extremely long (35.0 +/- 29.0 months).

Age Factors↗

PubMed1999

Incidence and clinical significance of transformation of atrial fibrillation to atrial flutter in patients undergoing long-term antiarrhythmic drug treatment.

AIMS: To investigate the rate of transformation of atrial fibrillation to atrial flutter in patients taking antiarrhythmic drugs for the prophylaxis of atrial fibrillation, we retrospectively analysed data from 305 consecutive patients with paroxysmal atrial fibrillation (155 male; mean age 63 +/- 11 years) treated with ventricular rate controlling drugs, antiarrhythmic drugs, or without drugs. METHODS AND RESULTS: At a mean follow-up of 9 months (range 1-24) all patients experienced recurrence of arrhythmia: 48 (14.6%, Group A) suffered Type 1 atrial flutter, and 257 (85.4%, Group B) atrial fibrillation. The relative rate of recurrence of atrial flutter vs atrial fibrillation was similar in patients without treatment or with ventricular rate controlling drugs (from 6.8% to 14.6%, P=ns). However, recurrence was higher (25%) in patients administered antiarrhythmic drug therapy. The relative risk in these patients was 3.02 times greater, compared with patients without treatment, or treated with rate controlling drugs (P<0.001). There were no differences between groups concerning the baseline clinical characteristics and the clinical consequences of the recurrence; patients with atrial flutter had a lower rate of conversion to sinus rhythm (42% vs 64%) and a higher rate of hospital admission (69% vs 36%) compared with those with atrial fibrillation. Six patients (8.5%) experienced 1:1 atrioventricular conduction during atrial flutter with a ventricular rate of 240-280 beats x min(-1). CONCLUSION: Our data suggest that the use of antiarrhythmic drugs for the prophylaxis of atrial fibrillation is associated with a threefold increase in the probability of Type 1 atrial flutter recurrence, as opposed to atrial fibrillation, which may have important clinical consequences, but which did not in our study.

Aged↗

PubMed1995

Radiofrequency catheter ablation versus modification of the AV node for control of rapid ventricular response in atrial fibrillation.

Atrial fibrillation is a common arrhythmia, which is frequently difficult to control. Symptoms and ventricular dysfunction may be caused by a rapid ventricular response to atrial fibrillation. Radiofrequency catheter ablation techniques for ventricular rate control have been developed, including AV node modification and AV node ablation with pacemaker implantation. For both AV node modification and ablation, radiofrequency energy is applied via a 4-mm tipped electrode catheter. For AV node ablation radiofrequency energy is applied near the compact AV node or His bundle via the right atrium, or occasionally at the His bundle via the left ventricle. For AV node modification radiofrequency energy is applied in the low middle or posterior septal right atrium near the tricuspid valve annulus. Both techniques can effectively control ventricular response to atrial fibrillation and the associated symptoms, although AV node modification is effective in only about 70% of patients compared to AV node ablation, which is effective in nearly 100%. In patients responding to AV node modification, maximal and mean ventricular response to atrial fibrillation is reduced by 25% to 35% chronically. Inadvertent AV block may occur during attempted AV node modification. It seems appropriate to attempt AV node modification prior to AV node ablation in patients with refractory atrial fibrillation and rapid ventricular response, in order to avoid the need for permanent pacemaker implantation. Although unproven, studies suggest that the mechanism by which AV node modification achieves ventricular rate control may be slow-pathway ablation in the low posterior septal right atrium.

Atrial Fibrillation↗

PubMed2002

[Therapeutic approach to the epidemic of atrial fibrillation].

Atrial fibrillation is the most frequent arrhythmia found in clinical practice and its prevalence increases with age which explains why it has reached epidemic proportions. The associated risk of thromboembolism and mortality worsen the prognosis in older patients with cardiac abnormalities. There are three kinds of atrial fibrillation according to the clinical relevance of the presentation: paroxysmal, persistent and permanent. Due to the clinically heterogeneous nature of this arrhythmia (it occurs with or without associated heart disease or symptom) and the difficulty of establishing appropriate treatment for each particular case, the American College of Cardiology, the American Heart Association and European Society of Cardiology, have established guidelines for the management of patients with atrial fibrillation. These guidelines were obtained through consensus by a Committee of Experts, after an exhaustive review of the most relevant English literature on atrial fibrillation in human beings from 1980 to 2000. The recent publication of these guidelines should facilitate and notably improve the management of patients with atrial fibrillation.

Algorithms↗

PubMed1975

Metabolic studies following thoracotomy for lung cancer with particular reference to postoperative atrial fibrillation.

Atrial fibrillation has proved to be a frequent complication after thoracotomy for lung cancer. In order to study the possibility that metabolic changes are the trigger mechanism of these arrhythmias, free fatty acids (FFA), glycerol, triglycerides, serum insulin and glucose were determined pre- and postoperatively in patients both with and without this postoperative complication. In the primary series of patients, FFA were found to be increased immediately after the start of the atrial fibrillation, partly in relation to the morning values and partly to the 24-hour curve. This is a possible expression of an increased lipolysis in a causal relationship to the arrhythmia. In another series of patients, the degree of lypolysis was demonstrated using the glycerol values. With this method, no signs of increased lipolysis were found in connection with the onset of atrial fibrillation. Thus, changes in the lipoid metabolism were not found to be the trigger mechanism of the postoperative atrial fibrillation. Reduced values of serum insulin and glucose were not demonstrated either during the uncomplicated postoperative period or at the start of atrial fibrillation.

Atrial Fibrillation↗

PubMed1997

Using the right drug. A treatment algorithm for atrial fibrillation.

Atrial fibrillation is the commonest sustained cardiac arrhythmia. Its incidence increases with age and in association with organic heart disease, in particular valvular heart disease, left ventricular dysfunction and in association with thyrotoxicosis and alcohol excess. Atrial fibrillation may present as paroxysms of self-terminating arrhythmia or as a sustained arrhythmia. In the former instance, management is directed towards suppression of paroxysms and will commonly involve class 1C, class 2 or class 3 agents. If atrial fibrillation is sustained, a decision as to the desirability of cardioversion must be made. If this can be achieved successfully, particularly if the episode was of brief duration and associated with a reversible cause, sinus rhythm may be preserved without further antiarrhythmic therapy. Otherwise prophylactic therapy as used for paroxysmal atrial fibrillation is appropriate. In patients who fail to respond to cardioversion, or in those with advanced organic heart disease, long-standing atrial fibrillation or marked dilatation of the left atrium in which case cardioversion is unlikely to be successful, the principal therapeutic strategy is to control ventricular rate. Classically, digoxin is used for this purpose. Additional agents which will slow the ventricular rates, such as beta-blockers, amiodarone or calcium channel antagonists (verapamil or diltiazem), may be necessary if the ventricular rate remains uncontrolled and continues to produce severe symptoms. In the event of failure of medical therapy to control ventricular rate, atrioventricular nodal modification or ablation may be appropriate.

Algorithms↗

PubMed2005

Nonpharmacologic stroke prevention in atrial fibrillation.

Atrial fibrillation is associated with significant mortality and morbidity. The burden of morbidity in atrial fibrillation is mostly due to stroke, one of the major causes of death and the leading cause of long-term disability. Although highly effective in prevention of thromboembolic stroke, several factors limit utilization of chronic oral anticoagulation therapy. Eradication of atrial fibrillation and restoration of effective atrial contraction by surgical methods, or recently, by percutaneous catheter ablation methods, are two attractive approaches for stroke prophylaxis. Surgical exclusion of the left atrial appendage has generated considerable interest in the past decades and it is now performed routinely during mitral valve surgery in many centers. Recently, minimally invasive and percutaneous methods for the exclusion of left atrial appendage have been introduced. Currently, these approaches are being evaluated in ongoing trials. This review will discuss the current status of nonpharmacologic methods in the prevention of stroke in atrial fibrillation.

Anticoagulants↗